// $cond returns the evaluated second argument if the first evaluates to true but the evaluated
// third argument if the first evaluates to false.
load('jstests/aggregation/extras/utils.js');

t = db.jstests_aggregation_cond;
t.drop();

t.save( {} );

function assertError( expectedErrorCode, condSpec ) {
    assertErrorCode(t, {$project: {a: {$cond: condSpec}}}, expectedErrorCode);
}

function assertResult( expectedResult, arg ) {
    assert.eq( expectedResult,
               t.aggregate( { $project:{ a:{ $cond:arg } } } ).toArray()[0].a );
}

// Wrong number of args.
assertError( 16020, [] );
assertError( 16020, [1] );
assertError( 16020, [false] );
assertError( 16020, [1,1] );
assertError( 16020, [1,1,null,1] );
assertError( 16020, [1,1,1,undefined] );

// Bad object cases
assertError( 17080, {"else":1, then:1} );
assertError( 17081, {"if":1, "else":1} );
assertError( 17082, {"if":1, then:1} );
assertError( 17083, {asdf:1, then:1} );

// Literal expressions.
assertResult( 1, [true, 1, 2] );
assertResult( 2, [false, 1, 2] );

// Order independence for object case
assertResult(1, {"if":true, "then":1, "else":2});
assertResult(1, {"if":true, "else":2, "then":1});
assertResult(1, {"then":1, "if":true, "else":2});
assertResult(1, {"then":1, "else":2, "if":true});
assertResult(1, {"else":2, "then":1, "if":true});
assertResult(1, {"else":2, "if":true, "then":1});

// Computed expressions.
assertResult( 1, [{ $and:[] }, { $add:[ 1 ] }, { $add:[ 1, 1 ] }] );
assertResult( 2, [{ $or:[] }, { $add:[ 1 ] }, { $add:[ 1, 1 ] }] );

t.drop();
t.save( { t:true, f:false, x:'foo', y:'bar' } );

// Field path expressions.
assertResult( 'foo', ['$t', '$x', '$y'] );
assertResult( 'bar', ['$f', '$x', '$y'] );

t.drop();
t.save( {} );

// Coerce to bool.
assertResult( 'a', [1, 'a', 'b'] );
assertResult( 'a', ['', 'a', 'b'] );
assertResult( 'b', [0, 'a', 'b'] );

// Nested.
t.drop();
t.save( { noonSense:'am', mealCombined:'no' } );
t.save( { noonSense:'am', mealCombined:'yes' } );
t.save( { noonSense:'pm', mealCombined:'yes' } );
t.save( { noonSense:'pm', mealCombined:'no' } );
assert.eq( [ 'breakfast', 'brunch', 'linner', 'dinner' ],
           t.aggregate( { $project:{ a:{ $cond:[ { $eq:[ '$noonSense', 'am' ] },
                                                 { $cond:[ { $eq:[ '$mealCombined', 'yes' ] },
                                                           'brunch', 'breakfast' ] },
                                                 { $cond:[ { $eq:[ '$mealCombined', 'yes' ] },
                                                           'linner', 'dinner' ] } ] } } } )
           .map( function( x ) { return x.a; } ) );
